/*
 *   Copyright 2011 Joshua Swank
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 */

package name.swank.language;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

import com.google.common.collect.ImmutableList;

public final class SymbolSequence
{
    private final Symbol[] symbols_;

    public SymbolSequence()
    {
	this((Collection<Symbol>) null);
    }

    public SymbolSequence(Collection<Symbol> symbols)
    {
	if (symbols != null)
	{
	    List<Symbol> symbolList = new ArrayList<Symbol>();
	    symbolList.addAll(symbols);
	    symbolList.removeAll(Collections.singleton(null));

	    symbols_ = symbolList.toArray(new Symbol[0]);
	} else
	    symbols_ = new Symbol[0];
    }

    public SymbolSequence(Symbol... symbols)
    {
	this(Arrays.asList(symbols));
    }

    public Symbol[] asArray()
    {
	return symbols_;
    }

    public List<Symbol> asList()
    {
	return ImmutableList.copyOf(symbols_);
    }

    public boolean isEmpty()
    {
	return symbols_.length == 0;
    }
}
